Ag Weather Forum

Severe weather season has been very active this year, with storm reports for tornadoes and wind damage running ahead of historical averages. That continues on the edge of this heat ridge the next few days.

A lot of attention has been paid to the hot and humid conditions developing across the Central United States for this week. And for good reason. Temperatures routinely in the 90s Fahrenheit are building throughout much of the Plains, southern Midwest, and Southeast with some readings eclipsing the 100-degree mark in the Central and Southern Plains.

But on the edge of this heat, the threat for severe storms is increasing.

An upper-level ridge of high pressure is building in the Southern Plains and with it, temperatures are soaring while humidity has increased. Dew point temperatures are solidly in the upper 60s to middle 70s. When combined with the heat, there is ample fuel for thunderstorms to develop.

Situations like this in the summertime are prime for creating several days of strong thunderstorms, which like to form on the edge of these heat domes and ride the edge of them. The current setup has this zone starting in South Dakota and Nebraska southeast into the Tennessee Valley which includes much of Iowa and Illinois.

We have already seen some small clusters develop Monday night into Tuesday morning with one cluster across central Iowa into south-central Illinois and another from southeast South Dakota into central Iowa. Both clusters have been small with limited impact, but have produced strong winds during the overnight hours that caused damage.

The setup through Thursday will favor these same areas with not only daytime thunderstorms, as is customary, but also potential for overnight severe storms that could produce damage. Storm chaser Reed Timmer (@ReedTimmerUSA) wrote on X this morning: "NOCTURNAL WIND BAG THREAT this evening through midnight from eastern Nebraska through southern Iowa, including Omaha to Des Moines! It's summertime ridge rider season, and I expect a few nights in a row of massive lightning shows but also widespread wind damage potential. The tornado threat appears quite low at this time!"

"Nocturnal wind bag" is not a meteorological term, but Reed's quirky personality underscores the threat of these overnight wind-producing severe storm clusters. The primary threat will be strong winds, and those could include gusts over 75 mph (hurricane strength). Derecho is not a term that I have seen just yet from the Storm Prediction Center (SPC) or others, but the ingredients are there for that possibility.

Hail and a couple of tornadoes may also occur but should be a secondary threat. Heavy rain due to the increased humidity, as well as thunderstorms "training" over the same areas in subsequent days, could lead to flooding as well. The main danger is for those thunderstorms to occur overnight, when people are sleeping and forced to react to a severe storm instead of preparing for it.

The path of potential thunderstorm clusters has not been modeled well and a ton of uncertainty is involved with the initiation and development of these clusters during the next few days. So anyone in the general vicinity of the SPC's "slight risk" or higher categories should prepare for potential for overnight storms. You can find updates from the SPC here: https://www.spc.noaa.gov/…

To find more weather conditions and your local forecast from DTN, head over to https://www.dtnpf.com/…

John Baranick can be reached at john.baranick@dtn.com

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